/*-
 * Copyright (c) 2006, 2007 FTS Team
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the FTS Team nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      HashFunctions.hpp
 *
 * $FTS$
 */
#ifndef _HASH_FUNCTIONS_HPP__
#define _HASH_FUNCTIONS_HPP__ 1

/**
  @file HashFunctions.hpp
  @brief Hashing functions and functors
*/
#include <FTSTypes.h>

namespace FTSS // FullTextSearchSystem
{

/**
  @fn inline UINT_32 HashFunc(CCHAR_P sKey, const UINT_32 & iLength)
  @brief Get hash from string
  @param sKey - String to hash
  @param iLength - String length
  @return Hashed value
*/
inline TokenHash_t HashFunc(CCHAR_P sKey, const UINT_32 & iLength)
{
	TokenHash_t ulHash = 5381;
	UCCHAR_P sEnd = (UCCHAR_P)sKey + iLength;

	while ((UCCHAR_P)sKey != sEnd)
	{
		ulHash += (ulHash << 5);
		ulHash ^= (TokenHash_t) *(UCCHAR_P)sKey++;
	}
return ulHash;
}

/**
  @struct HashHasher HashFunctions.hpp <HashFunctions.hpp>
  @brief Hash functors for various data types
*/
struct HashHasher
{
	/**
	  @brief Operator ()
	  @param sIKey - key to hash
	  @return hash for UINT_64 argument
	*/
	inline TokenHash_t operator ()(const UINT_64 & sIKey) const
	{
		TokenHash_t ulHash = 5381;
		CHAR_8 * szKey = (CHAR_8 *)(&sIKey);

		for (UINT_32 iI = 0; iI < 6; iI++)
		{
			ulHash += (ulHash << 5);
			ulHash ^= (TokenHash_t) *szKey++;
		}
	return ulHash;
	}

	/**
	  @brief Operator ()
	  @param sKey - string
	  @param iLength - string length
	  @return hash for character string
	*/
	inline TokenHash_t operator ()(CCHAR_P sKey, const UINT_32 & iLength) const { return HashFunc(sKey, iLength); }
};

/**
  @struct HashComparator HashFunctions.hpp <HashFunctions.hpp>
  @brief Comparator for two hash keys
*/
struct HashComparator
{
	/**
	  @brief Operator ()
	  @param arg1 - first argument
	  @param arg2 - second argument
	  @return true if arguments are equivalent
	*/
	inline bool operator ()(const TokenHash_t & arg1, const TokenHash_t & arg2) const { return arg1 == arg2; }
};

} // namespace FTSS
#endif // _HASH_FUNCTIONS_HPP__
// End.
